<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>Document</title>
    <style>
      .a {
        background-color: red;
      }
      .b {
        width: 200px;
        height: 200px;
      }
    </style>
  </head>
  <body>
    <div id="app">
      <div :class="arr" :style="[objSyle1,objSyle2]"></div>
    </div>
    <script src="https://cdn.jsdelivr.net/npm/vue/dist/vue.js"></script>
    <script>
      new Vue({
        el: '#app',
        data: {
          arr: ['a', 'b'],

          objSyle2: {
            'box-shadow': '1px 1px 1px 1px rgba(0,0,0,.3)'
          },
          objSyle1: {
            'border-radius': '50%'
          }
        }
      })
    </script>
  </body>
</html>
